An ink jet printing module ejects ink from an orifice in the direction of a substrate. The ink can be ejected as a series of droplets generated by a piezoelectric ink jet printing module. A particular printing module can have 256 jets in four groups of 64 jets each. A piezoelectric ink jet printing module includes a module body, a piezoelectric element, and electrical contacts that driving the piezoelectric element. Typically, the module body is a rectangular member into the surfaces of which are machined a series of ink channels that serve as pumping chambers for the ink. The piezoelectric element can be disposed over the surface of the body to cover the pumping chambers in a manner to pressurize the ink in the pumping chambers to eject the ink.
The properties of the piezoelectric element can affect the jetting properties of the printing module. For example, the volume of the drop of ink that is produced by the fire pulse can depend on the properties of each ink jet in the printing module. The droplet volume and velocity of the droplets can affect the quality of images produced by the droplets. By selectively ejecting ink droplets of a desired size at a desired velocity and at desired locations, or pixels, highly accurate images can be produced.